I'll bet there are at least a few interesting facts about geothermal energy in this list that are new to you. While geothermal energy has been in use for a long, long time, it has only recently begun to become commercially viable for large scale electricity production when compared to other options which involve the burning of fossil fuels. But with improvements in technology and a greater willingness to explore methods of generating electrical energy which do not have an adverse impact on the environment, it seems that geothermal energy is destined for bigger and better things.

These points also cover some of the geothermal power advantages and disadvantages which are important to keep in mind also. So here, in no particular order, are ten totally interesting facts about geothermal energy for your enjoyment:

1. Geothermal energy is not new

Humans cottoned on to geothermal energy quite some time ago, and evidence has been found of human settlement around hot water aquifers a few thousand years ago. I can just imagine those people taking a dip in the warm water, relaxing and taking a moment to get away from the troubles in the world. Seriously though, dating back to Paleolithic times, there is evidence of humans taking advantage of the natural geothermal energy which created heated pools.

Fast forward a little to ancient Rome and there is evidence of hot springs and aquifers being used to heat spaces in buildings. The oldest known spa pool though can be found in China on Lisan Mountain, dating back to the Quin dynasty and the 3rd Century B.C.oldest known spa pool on China's Lisan MountainCredit: Wikipedia

2. The first geothermal powered generator was Italian made

A gentleman by the name of Prince Piero Ginori Conti tested the first electricity producing geothermal energy powered generator. It was 1904 and the test was conducted at the Lardarell dry steam field. Considered a success, the equipment generated enough electricity to power up four lightbulbs.

3. Use of geothermal energy to produce electricity is growing

These days 24 countries (and counting) use geothermal energy to generate electrical power. New Zealand was the first country to build a geothermal power plant which generated electricity for distribution on the power grid, and it did so in 1958. Iceland is the country to most use geothermal energy in electricity production, with 30% of total electrical power coming from geothermal sources. The Philippines come a close second with 27%. The world's largest field of electricity producing geothermal plants can be found in California, at 'The Geysers' (how appropriate). These plants produce about 5% of the state's total electricity.

4. Geothermal energy is also used as a heat source

Not just a way for generating electrical power, which is a relatively recent application for geothermal energy, the most common way of using the heat of the earth here on the surface is for heating. This has been the case for some time, with the Romans using hot springs to heat public baths and underfloor heating systems in the first Century AD in the appropriately names town of Bath (then Aquae Sulis). The district heating system in Chaudes-Aigues in France has been operating since the 14th Century, and is still going strong. In Iceland, geothermal energy is used to heat around 90% of homes.

5. Drilling geothermal wells can trigger seismic events

Due to the nature of geothermal energy and the requirement to access heated liquids deep under the earth's surface, the drilling of wells is often necessary. These wells though have the potential to trigger seismic events, which is not surprising really, considering the depths that these wells are dug to. A project in Basel, Switzerland which was to have generated electricity from injecting water into wells dug to a depths of 5km was abandoned after a series of small earthquakes were attributed to the geothermal plant's activities.

6. Geothermal energy is sustainable (kind of)

While many pundits like to advertise geothermal energy as being totally sustainable, it is technically not. True, the plants power themselves and require no fuel to run, but think about it - we are essentially extracting heat from the planetary core to make electricity - this will have lasting effects. Sure, the amount of heat extracted is minute by planetary standards, but still - the activity does have an effect, and is therefore not infinitely sustainable. This is illustrated by the fact that while still operational, the levels of electricity production at the Lardarello (Italy), Wairakei (New Zealand) and the Geysers (USA) have dropped due to local depletion.

7. Lower levels of heat are now required to produce electricity

Thanks to improvement in technology and improved power plant designs, the temperature that the steam extracted must be at is much lower than in the early days of geothermal power plants. In fact the newer design of the binary cycle plant in Chena Hot Springs, Alaska produces electricity from temperatures as low as 150 degrees farenheit (57 celcius). This has obvious benefits which would reduce the reliance on dee drilling of geothermal wells which risk seismic activity.interesting facts about geothermal energyCredit: ThinkGeoEnergy on Flickr.com

8. Geothermal energy is not exactly clean energy

It's quite popular to say that geothermal energy is a clean, green way of generating electrical power, but that is not entirely true. As part of the steam extraction process, other minerals and gasses are also brought to the surface and released. These include carbon dioxide, methane, ammonia and hydrogen sulfide. These contribute to global warming and acid rain - however the levels at which they are released is smaller than conventional fossil fuel fired power stations - about one eighth of the levels produced by a coal burning plant. While not huge amounts, the fact that these emissions occur are real issues for geothermal energy proponents.

9. It's getting cheap to produce geothermal energy

While it is technically true that geothermal energy is on an equal par when it comes to cost when compared to coal fired power plants, don't look too closely. Reductions in costs thanks to the reduced need to drill to major depths and improvements in plant design and efficiency have combined to improve the financial viability of geothermal powered electricity production - but it doesn't end there. Finance can be hard to get for geothermal power plants and the levels of finance required is high too - and with about 20% of well drills failing, it;s a big risk to take. There are also government subsidies in place which expire in 2013 and will not necessarily be continued beyond that date.

10. There's a whole bunch of geothermal potential down there

Surveys have determined that there is a whole lot of geothermal energy under the earth's surface which is just waiting for us to make use of it. The resources available are more than the reserves of oil, gas, coal and uranium combined. But what are the long term effects of using this energy, of removing it from the planet - isn't it risky? Well yes it is, and this is why there is a whole lot of enquiry going on int the effects of removing this heat from the earth, effectively cooling the planetary core.

I hope you have enjoyed these interesting facts about geothermal energy - it's a really interesting subject, sure to come up more often in the future. If you know another geothermal fact that you think should be included, leave a comment, we'll be glad to hear about it!